Folding bicycle

ABSTRACT

The subject of the invention is a bicycle with a drive on front wheel, which after turning the handlebar by cca 110° relative to the frame of the front wheel considerably reduces its overall dimensions and which can be easily adjusted tor two persons. 
     In this bicycle the train e consists of the frame ( 1 ) of the front wheel ( 15 ) and the frame ( 2 ) of the rear wheel ( 16 ), with the seat ( 19 ) and a back-rest ( 14 ) fixed. Both frames are coupled with the joint ( 3 ) and the crossed line transmission ( 10, 11, 12 ). In this coupling the axis of the joint ( 3 ) which is a part common to both frames intersects the floor surface in the point (C) at an angle of 69°±3°, at a distance of 20±4 cm behind the point of contact of the front wheel with the floor. Applied drive system ( 18 ) is placed preferably on the axis of driven wheel, and it consists of the crank system ( 17 ), planetary transmission and the one-way clutch. The handlebar ( 7 ) is mounted rotationally in the swivel axle ( 4 ) of the frame ( 1 ) of the front wheel and is immovably fixed through the swivel axle with the big wheel ( 10 ) of the crossed line transmission. The swivel axle ( 4 ) of the frame ( 1 ) has two bearings ( 8 ), ( 9 ), where the bearing ( 8 ) at the handlebar ( 7 ) is a bearing of small friction momentum, while the bearing ( 9 ) at the wheel ( 1 ) of the transmission is a transverse slide bearing with big friction momentum. The ratio of the crossed line transmission ( 10, 11, 12 ) equals to 1.4±0.1:1. The small wheel ( 11 ) of this transmission is immovably fixed to the frame ( 2 ) of the rear wheel ( 16 ) in the axis of the joint ( 3 ) coupling both frames ( 1 ), ( 2 ), and the big wheel ( 10 ) of the transmission is immovably joined through the swivel axle ( 4 ) with the handlebar ( 7 ) and rotates in the axis ( 6 ) of the swivel axle ( 4 ) of the frame ( 1 ). The line ( 11 ) joining the wheels ( 10  and  12 ) of the transmission crosses between the big wheel ( 10 ) and two relief rollers ( 13 ) placed close to the wheel ( 10 ).

The subject of the invention is a bicycle with a drive on at Least afront wheel.

Construction of this bicycle makes possible to considerably and veryquickly decrease its overall dimensions and to adjust it easily for twopersons.

The bicycles with the drive on the front wheel are known for long time(SHIRE & BONESHAKER 1870, or DEKSTER 1869), and functionality of theoverall dimensions reduction is realised in many ways.

In known bicycles the functionality of folding is realised most often byuse of additional constructional elements. The bicycle known from Polishapplication P.344428 is tor example fitted with additional joints makingpossible to “break” the bicycle in places of junction of the frame beamsand in the handlebar plane. Introduction of such additional elements istroublesome because it lengthens the time of the bicycle preparation fordriving, increases its weight and cost.

Folding bicycle is known as well from Polish application P.354284. Inthis bicycle rear rocker is joined to the end of the frame throughtelescopic suspension of rear wheel. Front and rear wheels are joined tofront and rear rockers, respectively. Telescopic elastic suspension offront wheel, rail suspension of rear wheel, the handlebar axle and thetreadles with cranks are fitted with quick releases. Functionality offolding is realised in this bicycle also with use of additionalelements.

Also from Polish application P.292655 a bicycle is known with arhomboidal frame cut along shorter diagonal, where these cuts aresubsequently joined separably with articulated locks. The bicycle isfolded by releasing of locks on the frame.

A bicycle with rear drive is known from Polish application P.377279,where the axis of the handlebar fixed to the frame runs through thepoint of intersection of front wheel with the floor, and the angle madeby this axis with the floor equals about 70°.

To summarize, all known constructions of the bicycles with functionalityof folding require usage of additional elements.

The aim of the invention is to propose a bicycle construction that makespossible easy, fast (less than 1 sec.) and considerable redaction of itsoverall dimensions. The construction should be light, comfortable, easyto keep it clean, with good driving qualities, and making possible easyadjustment for two persons.

The bicycle according to the invention has the wheels joined by theframe beams, a handlebar, a seat and a drive. In this bicycle the frameconsists of the frame of the front wheel fitted with the driving systemwith an axis of rotation comprised within this wheel, and the rear wheelframe, with a seat and a back-rest fixed. Both frames are coupled by ajoint and a crossed line transmission. In this coupling the axis of thejoint being common to both frames intersects the floor surface at anangle of 69°±3°, at a distance of 20±4 cm behind the point of contact ofthe front wheel with the floor. According to the invention the rearwheel may also be fitted with the driving system, like the front wheel.The driving system applied is placed on the axis of driven wheel and itis a treadle crank system. One-way clutch and planetary transmission,preferably an automatic variable ratio transmission are placed on anaxis of rotation of this wheel. The handlebar is fixed rotationally in aswivel axle of the front wheel frame and is immovably joined through theswivel axle with big wheel of the crossed line transmission. The swivelaxle of the front wheel frame has two bearings, where the bearing closeto the handlebar has small friction momentum, preferably the ballbearing, while the bearing at big wheel of the crossed line transmissionis a transverse slide bearing with big friction momentum.

The ratio of the crossed line transmission equals to 1.4±0.1:1. Smallwheel of this transmission is immovably fixed to the rear wheel frame inan axis of the joint that couples both frames, and big wheel of thetransmission is immovably joined with the handlebar and it rotates inthe axis of the swivel axle of the front wheel frame.

The line joining both wheels of the transmission is crossed between thebig wheel and the relief rollers placed close to big wheel of thetransmission.

The bicycle according to the invention is comfortable, easy inmaintenance and is characterized by low failure frequency. It has gooddriving qualities and is characterized with little impact of changingforces during pedalling on the steering system. It may be easilyadjusted for two persons and quickly reduced in overall dimensions.

The invention is explained in preferred embodiments shown on thedrawings, where FIG. 1 shows a single-seat bicycle. FIG. 2 shows thisbicycle after reduction of overall dimensions. FIG. 3 shows a bicyclefor two persons, and FIG. 4 shows the bicycle for two persons in foldedstate.

The bicycle has the front wheel (15) with a diameter of 28″, the rearwheel (16) also with the diameter of 28″. The wheels are coupled withcombined frame consisting of the frame (1) of the front wheel (15) andthe frame (2) of the rear wheel (16). The frames (1) and (2) are coupledby the joint (3) and by the crossed line transmission (10, 11, 12) witha ratio of 1.4:1. The frame (1) has the swivel axle (4) with thehandlebar (7) fixed rotationally around the axis (6). The swivel axle(4) with the handlebar (7) fixed has two bearings (8) and (9). Thebearing (8) is placed close to the handlebar (7) and it is common bailbearing. At the big wheel (10) of the crossed line transmission thebearing (9) is placed, which is a transverse slide bearing with highfriction momentum. The handlebar (7) is immovably joined through theswivel axle (4) with the big wheel (10) of the crossed line transmission(10, 11, 12). This transmission has a ratio of 1.4:1 and its small wheel(11) is fixed immovably on the axis (5) of the joint (3) joining theframes (1) and (2).

If the handlebar (7) turns against the frame (1), it makes the frame (1)to turn relative to the frame (2).

The bearing (9) of the swivel axle (4) is relieved with use of tworelief rollers (13) in case of equal line tension on both sides of thetransmission, The rollers (13) are placed close to the wheel (10) of thecrossed transmission, and the line (12) of the line transmission iscrossed between the big wheel (10) and the rollers (13). The differenceof the line (12) tensions on both sides of the transmission made by theframe (1) turn relative to the frame (2) without the handlebar turningrelative to the frame (2) generates on both sides of the transmission,proportional friction momentum in the bearing (9), which restrainsmovement of the frame (1) relative to the frame (2).

If by turning the handlebar (7) relative to the frame (1) one generatesa difference in the line (12) tension on both sides of thetransmission., the momentum of force applied to the handlebar relativeto the rotation axis (5) of the joint (3) compensates this difference intension making possible to turn the handlebar easily.

The front wheel of the bicycle is driven by the crank drive system (18)with the treadles (17). The drive system consists of the one-way clutchand the planetary transmission, placed on the axis of rotation of thewheel (15).

In preferred embodiment the axis (5) of the joint (3) which is a partcommon for both frames (1) and (2) intersects the floor surface in thepoint (C) at an angle of 60°, and the distance of this point from thepoint of contact of the first wheel (15) with the floor equals 20 cm.

In the beam of the frame (2) of the rear wheel the seat (19) is mounted,fitted with the back-rest (14). On this beam, behind the back-rest (14)second seat may be mounted, if the bicycle shall be adjusted for twopersons (FIG. 3). This embodiment requires also replacing the rear wheel(16), preferably by a wheel 26″, with the crank drive similar to that inthe front wheel.

1. A bicycle fitted with two wheels joined through the beams of theframe, a handlebar, a seat and a crank drive system, which is installedat least on the front wheel characterised in that it has a frameconsisting of a frame (1) and a frame (2), where the frame (1) is theframe of the front wheel (15) and has a swivel axle (4) with fixedhandlebar (7) joined rigidly through the swivel axle with a big wheel(10) of a crossed line transmission, while the frame (2) is the frame ofthe rear wheel (16) and is fitted with at least one seat (19) with aback-rest (14) and both frames are coupled by a joint (3) and thecrossed line transmission (10, 11, 12) so, that the axis (5) of thejoint (3) which is a part common to both frames intersects the floorplate in a point (C) at an angle of 69°±3°, at a distance of 20±4 cmfrom the point of contact of the front wheel (15) with the floor.
 2. Thebicycle according to claim 1 characterised in that the rotation axis ofthe drive system (18) consisting of a one-way clutch, a planetarytransmission and a crank system (17) is placed inside driven wheel,preferably on the rotation axis of this wheel.
 3. The bicycle accordingto claim 1 characterised in that the swivel axle (4) of the frame (1),where the handlebar (7) is rotational mounted, has two bearings (8) and(9), where the bearing (8) is placed at the handlebar and is a bearingof small friction momentum, preferably common ball bearing, while thebearing (9) is placed at the big wheel (10) of the crossed linetransmission (10, 11, 12) and is a slide bearing of big frictionmomentum.
 4. The bicycle according to claim 1 characterised in that asmall wheel (11) of the crossed line transmission (10, 11, 12) isimmovably fixed to the frame (2) in the axis (5) of the joint (3), andthe big wheel (10) is immovably joined through the swivel axle (4) withthe handlebar (7) and rotates in the axis (6) of the swivel axle (4),besides the line (12) joining both wheels (10 and 11) of thetransmission crosses between the big wheel (10) and two relief rollers(13) placed close to the big wheel (10).
 5. The bicycle according toclaim 5 characterised in that the crossed line transmission (10, 11, 12)has a ratio of 1.4±0.1:1.